Method of treating paints



o for attaining o kind,

3 the 1ron group,

Patented Oct. 26,1926.

I ROBERT Hazel-men STUTTGART,

GERMANY, Assmnonmo THE 1 or s'rurreanr, GERMANY.

annie FI-Qif...

FIRM: PAUL LEonLnn,

METHOD or TREATING PAINTS.

No iDrawing. Application flled September i, 1923, Serial No. 661,527, and in Germany August 1, 1922.

. My invention refers to paints and more especially to means for preventing a film of dried paint from cracking and tearing. It is an object of my invention to provide means this end in a particularly simple and efiective manner. j

According to .the present invention the paint,- which as a ruleconsists of a pigment and a vehicle or carrier of some suitable tains the hydroxid of one or several of the metals of the iron group (which group comprises,,.besides iron, aluminum and chromium), a small quantity of such hydroxid,

5 which has a fiocculent character, being admixed with the paint in a state of extremely fine subdivision, suchas can be obtained by causing the hydroxid to be precipitated, for instance from a solution of a salt, right in 0 the paint itself. The finely divided flocculent hydroxid will form an extremely thin network of metal oxid in the paint after drying, this oxid network forming a strong protective coating which effectually prevents the film of dry paint from tearing and cracking.- In 100 parts by weight of the paint not more than one part and in the majOl'lty of cases 0.2 parts and even less of the metal compound will be present.

it In order to carry my invention into practice, 1 may proceed in diiierent ways.

I may, for instance, mix the paint, ready for use, .by vigorous stirring with a highly concentrated solution of a salt of a metal of thereby forming an emulsion in which the salt solution is finely subdivided. By adding understirring the required quantity of a highly concentrated solution of an alkali 1 hydroxid, the metal hydroxid is formed is precipitated as an which, being insoluble, extremely fine flocculent constituent.

I may for instance add to 1,000 grams of an oil paint grams of a Watery solution containing per cent aluminium sulfate (calculated free of crystal water). The mixture is stirred vigorously so that an emulsion is formed. To this emulsion there are added under stirring 4.8 grams of'a watery solu tion containing per cent caustic soda.

The solution of sodiumsu1fate, which forms a separate layer, is'removed.

Another method of obtaining the novel product consists in admixing with the paint a complex compound of a hydroxid of 5,

preferably of a'liquid character, con-.

such as aluminium sulfate,

. chloric acid are added drop metal of the iron group (iron, aluminum,

chromium) with an organic oxy-acid or other oxy-compou'nd, such as tartaric acid and citric acid or sugar, starch and the like. After some time the metal hydroxid itself will separate out in the paint and will be emulsion thus'iormed are added under stirring 4.8 grams of a watery solution. contain 111g 30 per cent caustlc soda. The water which separates off is removed in any suitable manner. a I

Still another method of making a stable paint according to this'invention consists in mixing with the paint the. hydrosole of one or several oxide of the metals, of the iron group (iron, aluminiunr and elu'oiniuin). In the emulsion thus formed the metal oxid precipitates of itself in a state of extremely fine subdivision.-

Thus for instance 20 cubic centimeters of an aluminium hydroxid hydrosole solution.

are admixed under stirring with 1,000 grains The Water which. settlesof an oil paint. after some time is removed in any suitable manner. The'hydrosole solution is obtained in a Well known manner, for instance by precipitating 50 cubic centimeters of aluminium chloride solution, containing 1.124; grams of aluminium oxid, with ammonia. The precipitate is quickly rinsedwith water and is heated to boiling with 250. cubic centi meters of water. To the boiling mixture 20 cubic centimeters of a 1/20 normal hydroby drop. The colloidal solution thus obtained is carefully concentrated to a volume of 40 cubic centimeters, one half of which is added to 1000 grams o:t the paint; as above described.

If paints containing fatty oils are treated according to this invention, the'water admixed with them will settle on top of the paint. On the other hand, in bituminous paints containing tarry or asphalt-like con stituents the water will remain in the emulsion and will evaporate while-the paint is drying.

I w sh it.

to be understood that I do not iron group and precipitating in said paint an insoluble hydroxide of said metal by the addition of the theoretical amount of an alkali hydroxide, Without adding an amount of water as large as the amount of said nonaqueous vehicle.

In testimony whereof I have aflixed my signature.

D12. ROBERT MEZGER. 

